1. Department of Otolaryngology-Head & Neck Surgery, Kagawa Rosai Hospital, Kagawa, Japan
2. Department of Otolaryngology-Head & Neck Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
3. Department of Otolaryngology, Kochi Health Sciences Center, Kochi, Japan
4. Department of Otorhinolaryngology, School of Medicine, International University of Health and Welfare, Narita, Japan